Alert Level 1 up over Bulusan Volcano — PHIVOLCS

MANILA, Philippines — PHIVOLCS on Tuesday raised the Alert Level 1 on the Bulusan Volcano in Sorsogon, indicating a low level of unrest there. 

State volcanologists in a bulletin said they have recorded 124 volcanic earthquakes from the Bulusan since May 8.

The increased occurrence of these tremors, they said, could be followed by "steam-driven or phreatic eruptions at the summit crater or from flank vents on the upper to middle slopes."

"Alert Level 1 status now prevails over Bulusan Volcano, which means it is currently in an abnormal condition," PHIVOLCS added. 

Bulusan, a stratovolcano considered as among the most active in the country, had the same situation in July 2020.

The agency said its real-time electronic tilt monitoring saw a "sustained inflation of the upper slopes" that began in March 6.

It added: "These parameters indicate indicate that volcanic processes are underway beneat the edifice that are likely caused by shallow hydrothermal activity."

As a result, PHIVOLCS warned that entry to the Bulusan's 4-kilometer radius Permanent Danger Zone be strictly prohibited. 

Local officials should monitor too the 2-km Extended Danger Zone on the southeast sector due to increased possibilities of "sudden and hazardous phreatic eruptions."

"Civil aviation authorities must also advise pilots to avoid flying close to the volcano's summit as ash from any sudden phreatic eruption can be hazardous to aircraft," PHIVOLCS said. 

Residents within valleys and along rivers or stream channels should be vigilant as well for sediment-laden stream flows and lahars in the event that heavy and prolonged rainfall occur from a phreatic eruption.